procharged truck running lean

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07-08-2013, 11:05 PM

#11

kelsey_canard

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Originally Posted by jaradt2013

i jus wasnt suspecting o2 sensors or really any sensors considering its not throwing any codes last code i had was ast month and it was p0300 and it was caused by two bad msd coil packs changed them and erased codes and light hasnt been back on

I haven't seen a lot of bad o2 sensors, but when I have seen them throw a code for low voltage, the pcm makes a faux narrowband signal. 450mv iirc, so it won't affect the fuel trims at all.

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07-08-2013, 11:07 PM

#12

jaradt2013

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alright well tomorrow after i get off work i will try disconecting the maf and battery like you suggested and see what happens and then i will get back with you i appreciate you for your help thanks

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07-08-2013, 11:13 PM

#13

kelsey_canard

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Originally Posted by jaradt2013

so if i unplug maf and then disconnect battery and then reconect battery and start it and it runs fine then it is the maf bad ? sorry to sound so stupid but im new to ls based engines hate to say it but ive always had mustangs so im kinda lost in tying to figure this out never had anything like this happen... but if its not the maf then fuel pressure regulator maybe or i just dont understand what would causeit to start and idle perfect for 45 seconds and then drop off lean and the line back out after playing with the trottle and not throw any engine codes im just lost

Yes. Not necessarily bad Maf, but the Maf not metering the air coming into the engine correctly. Basically, all air that enters your motor needs to go through the maf sensor. The sensor calculates the engines airflow, and fueling is based off of it. I'm sure someone else can describe it better than me though.

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07-11-2013, 09:06 PM

#14

jaradt2013

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well i un did battery and unplugged maf and then hooked battery back up and started it with maf unplugged and idled like crap so i cut it off hooked maf back up started it and it did same thing ran fine for about a minute then got real lean and then lined out after i plaed with the throttle for a minute or two.

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